/*
 * File    : ED2KHasher.java
 * Created : 16-Feb-2004
 * By      : parg
 * 
 * Azureus - a Java Bittorrent client
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details ( see the LICENSE file ).
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package org.gudy.azureus2.core3.util;

/**
 * @author parg
 * 
 */

public class ED2KHasher {
    public static final int BLOCK_SIZE = 0x947000;

    protected MD4Hasher current_hasher = new MD4Hasher();
    protected MD4Hasher block_hasher;

    protected int current_bytes;

    public ED2KHasher() {

    }

    public void update(byte[] data) {
        update(data, 0, data.length);
    }

    public void update(byte[] data, int pos, int len) {
        int rem = len;

        while (rem > 0) {

            int space = BLOCK_SIZE - current_bytes;

            if (rem <= space) {

                current_hasher.update(data, pos, rem);

                current_bytes += rem;

                break;

            } else {

                if (block_hasher == null) {

                    block_hasher = new MD4Hasher();
                }

                if (space == 0) {

                    block_hasher.update(current_hasher.getDigest());

                    current_hasher = new MD4Hasher();

                    current_bytes = 0;

                } else {

                    current_hasher.update(data, pos, space);

                    pos += space;
                    rem -= space;
                    current_bytes += space;
                }
            }
        }
    }

    public byte[] getDigest() {
        // data that is a multiple of BLOCK_SIZE needs to have a null MD4 hash appended

        if (current_bytes == BLOCK_SIZE) {

            if (block_hasher == null) {

                block_hasher = new MD4Hasher();
            }

            block_hasher.update(current_hasher.getDigest());

            current_hasher = new MD4Hasher();
        }

        if (block_hasher == null) {

            return (current_hasher.getDigest());

        } else {

            if (current_bytes > 0) {

                block_hasher.update(current_hasher.getDigest());
            }

            return (block_hasher.getDigest());
        }
    }

    /*
     * public static void main( String[] args ) { SESecurityManager.initialise(); ED2KHasher hasher = new ED2KHasher(); try{ FileInputStream fis = new
     * FileInputStream( "C:\\temp\\dat.txt"); byte[] buffer = new byte[1024*1024]; while( true ){ int len = fis.read( buffer ); if ( len <= 0 ){
     * break; } hasher.update( buffer, 0, len ); } }catch( Throwable e ){ e.printStackTrace(); } byte[] bah = new byte[BLOCK_SIZE]; Arrays.fill( bah,
     * (byte)'a' ); hasher.update( bah ); try{ FileOutputStream fos = new FileOutputStream( "C:\\temp\\data.txt" ); fos.write( bah ); fos.close();
     * }catch( Throwable e ){ e.printStackTrace(); } System.out.println( "hash=" + ByteFormatter.encodeString( hasher.getDigest())); }
     */

}
